wallace



March 5,1940. v B, WALLACE I2,192,422

DRAFTING INSTRUMENT CHUCK AND WRENCH Filed April l0, 1939 Patented Mu. s. 1940 UNITED STATES 2.122.422 mmc INSTRUMENT cnucx um warmen Vard B. Wallace, Sierra Madre, Calif., assignor to Vai-d Mechanical laboratory, a copartnerahip composed of Vai-d B. Wallace and Paul ll. Ford Application April 10, 1939. Serial No. 266,967

4Claims.

My invention relates to drafting machines and has particular reference to an instrument chuck and wrench for use with drafting machines which nds particular utility when employed 'as a means 5 for detachably securing one or more interchangeable instruments to a drafting machine head.

Drafting machines ordinarily comprise a parallel mechanism cooperating with a xed support in such manner as to permit movement of a head portion over a drawing surface in such fashion that the angular position of the head portion relative to any predetermined base line on the drawing board is maintained at a constant value.

The head portions of lsuch drafting machines are ordinarily provided with a means for holding various drafting instruments, such as scales, straight edges, rulersl or similar instruments. Because a different type of instrument is required for different types of drafting operations and different phases of a particular piece of drafting work, these instruments are detachably secured to the drafting machine head by providing a tapered chuck receptacle in the head portion of the machine and a similarly tapered member secured to each of the instruments so that the tapered member may be forcibly inserted in the tapered receptacle to secure the instrument to the drafting machine head.

This type of construction, while providing the advantages of interchangeability of instruments,

has the outstanding disadvantage in that the instruments are apt to work loose from the head so that inaccurate work is done with the machine.

receptacle once it has become'firmly wedged,

therein, also gives rise to considerable damage to the instrument.

It is therefore an object of my invention to.

overcome the aforementioned disadvantages found in drafting machineconstructions by pro-- viding an instrument chuck and wrench construction providing for the ready and secure engagement of the instrument with thedrafting ma.

chine head and the ready disengagement of the instrument therefrom.

. engagement with said slot so that rotation of said It is also an object of my invention t'o provide a drafting machine head employing a chuck receptacle adapted to frictionally receive a chuck member secured to an instrument to be used with the drafting machine head and a wrench for 5 forcing the chuck member into or out of the chuck receptacle. l

It is a further object of my invention to provide an instrument chuck construction of the character set forth in the preceding paragraphs which employs a chuck wrench for applying Va'- wedging force between a chuck membeT and a chuck receptacle for forcibly inserting the member into the receptacle and for effecting the removal of the member therefrom.

It is also an object of my inventionv to provide a drafting machine construction of the character set forth in the preceding paragraphs wherein the chuck receptacle and chuck member are provided with opposed pressure faces and in which' a chuck wrench is provided with a `cam member engageable with said .pressure faces to force the chuck member into engagement with the chuck receptacle and to forcibly withdraw the member therefrom.

It is also an object of my'invention to provide a drafting machine head of the character set forth in the preceding paragraphs in which a tapered chuck receptacle is provided with an aperture and a tapered chuck member for insertion in said receptacle is provided with a slot disposable adjacent said aperture and in which is employed a chuck wrench having a portion engageable with said aperture and a pin member for chuck member will move said chuck member relative to said chuck receptacle.

Other objects and advantages of my invention will be apparent from astudy of the following specification, read in connection with the accompanying drawing, wherein: I l

Fig. 1 is a plan view illustrating a well known form of drafting machine fitted with a drafting head employing an instrument chuck of my invention; A g

Fig. 2 is a fragmentary view representing a porgtion of Fig. 1 enlarged to show the details of construction of the chuck parts employed;

Fig. 3 is a perspective view showing one form of chuck wrench; Y

Fig. y4 is a fragmentaryvertical section taken .substantially along the line IV-IV of Fig. 2 to showthe relative relationship betweenthe chuc parts and the chuck wrench;

Fig. 5 is a diagrammatic view illustrating the 55 relative positions of the chuck members and the chuck .wrenchat the beginning of an operation to secure an instrument to the drafting machine Fig. 7 is a view similar to Figs. 5 and 6 showing l the relative disposition of parts at the time the instrument is firmly xed to the drafting machine head.

Referring to the drawing, I have illustrated in Fig. 1 a typical drafting machine construction employing a parallel mechanism comprising a xed supporting member I secured in any suitable fashion to the upper edge of a drawing board or working surface 2. The fixed support I pivotally mounts a parallel mechanism 3, illustrated in Fig. 1 as being of the endless band type which employs a pair of pivotally jointed arms 4 and 5 which carry at their extremities pulleys enclosed by pulley guards 6, 1, and 9. 'I'hese pulleys co- -operate with a pair of endless bands I 0 and I I in a well known manner to maintain the drafting machine head 9 in a fixed angular position relative to the surface of. the drawing board 2, while permitting translatory movement of the head 9 thereover.

The drafting machine head 9 of my invention is provided in the preferred embodiment thereof with a scale supporting member I2 which may be detachably secured to the head 9 by means of suitable securing devices I3 and I4. The'scale supporting member I2 preferably includes a pair of arm sections I5 and I6 disposed at right angles relative to each other and adapted to carry various instruments, such as a scale I1 or a straight edge I8.

As illustrated in Figs. 2 and 4, each of the arms I5 and I6 of the scale supporting member I2 is provided on its under side with a chuck receptacle I9 communicating with the ends of the arm portions I5 or I6 and adapted to receive and frictionally retain a chuck member 22 secured to the scale Il or other drafting instrument. Frictlonal retention of the chuck member 22 may be obtained by forming the chuck receptacle I9 with side Wall portions 20 and 2I angularly disposed relative to each other to provide an elongated, tapered receptacle and by forming the chuck member 22 with a plate-like portion having opposed edge faces 25 and 26 which are angularly disposed relative to each other so as to provide a taper corresponding to the taper ofthe side walls 20 and 2|. It will be observed that when the chuck member 22 is tightly wedged within the tapered receptacle I9, its angular position relative to the drafting machine head 9 is fixed.

In order to permit angular adjustment of the instrument I'I relative to the head 9, I prefer to secure the chuck member 22 to the upper surface of the scale Il by means of screws 23 and 24, the

screw 24 passing through an elongated slot 2l in the chuck member 22 so that loosening of this screw will permit angular adjustment of the scale I1 relative to the chuck member 22 and so that tightening of the screws 23 and 24 will lock the lscale in such adjusted angular position.

In order that the chuck member 22 may be forcibly inserted within the tapered chuck receptacle I9 and readily removed therefrom, I

provide in the upper surface of the scale supporting member I2 a cylindrical bore 28A which communicates with the upper surface of the .receive a pin portion 33 formed integrally or se cured to the lower end of the shank portion 29 -of the chuck wrench 30. The pin portion 33 is eccentrically disposed relative to the axis of rotation of the chuck wrench 30 so that as the chuck wrench 30 is rotated about its longitudinal axis, the pin 33 will describe a small circle.

The operation of the chuck and chuck wrench of my invention may best be understood by having reference to Figs. 5, 6 and 7. At the time the chuck member 22 is loosely `or preliminarily inserted in the chuck receptacle I9, the parts willbe disposed in the approximatepositionsillustrated in Fig. 5 with the slot 32 disposed near the outside edge of the circular aperture 28. The chuck member 22 may then be forcibly engaged in the chuck receptacle I9 by inserting the chuck wrench 30 in such a manner that the pin portionv 33 is received in the slot 32 and the shank portion 29 is received in the aperture 2li.A Rotation ofthe chuck' wrench 30 by means of the handle 3| will thereupon move the pin portion 33 -through a circular path and tending generally inwards relative to the receptacle I9-so that the parts progressively assume the positions illustrated in Figs.. 6 and 7.

It will be observed that the provision of the slot 32 for receiving the eccentric pin 33 permits the rotational movement of the pin 33 to impart a purely sliding or translatory movement of. the chuck member 22. When the parts are finally moved tov a position corresponding to that illustrated in Fig. 7, the chuck member 22 has been moved inwardly within the` receptacle I9 sufficiently far to forcibly engage the coacting tapered surfaces and fixedly secure the chuck member 22 and the instrument I1 carried thereby to the drafting machine head 9. The removal of the instrument I'l from the drafting machine head 9 may be readily accomplished by reversing the above described operation.

While I have described the preferred embodiment of my invention as employing a chuck wrench which includes a' cylindrical shank adapted to be received in a circular aperture and a circular eccentric pin adapted to be received in an elongated slot in the chuck member, it is to be understood that other shapes of coacting members may be used.

Attention is called to the fact that the chuck wrench of my invention acts as a cam member between opposed pressure faces carried, respectively, by the scale supporting member I2 and the chuck member 22 to cause relative translatory movement between these members and forcibly engage the member in the receptacle ormove the member out of the receptacle, de-

pending upon the direction in which the wedgthe equally ready removal of the instrument therefrom.

While I have shown and described the preferred embodiment of my invention,I I do not desire to be limited to any of the details of construction shown or described herein, except as defined in the appended claims.

I claim:

1. In a chuck construction for use with drafting machines employing a scale supporting member, the combination of: a chuck member; a chuck receptacle formed in said scale support y for receiving said chuck member; means in said chuck receptacle for frictionally retaining said chuck member; one pair of opposed pressure faces on said chuck member and on said scale support; and another pair of oppositely directed opposedpressurefacesdisposedonsaidchuckmember and said scale support adjacent said one pair, whereby a chuck wrench having a wedging means may be interposed between both pairs of said opposed pressure faces and rotated to apply a wedging force therebetween to force said member inwardly and outwardly of said receptacle.

2. In a chuck construction for use with drafting machines employing a scale supporting member, the combination of: a chuck receptacle formed in said scale support; a chuck member insertable in said receptacle; means in said receptacle for frictionally retaining said member;

an opening in said support communicating with said receptacle; and a recess. in said member disposed in a position to be placed in overlapping relation with said opening when said member is inserted in said receptacle, whereby a wrench may be inserted through said opening and engaged with said recess and moved to bear against the sides of said opening and said recess .to move said member inwardly or out- 40 wardiy of said receptacle as desired.

3. In a chuck construction for use with drafting machines employing a scale supporting member, the combination of: a chuck member; a chuck receptacle formed in said scale support for receiving said chuck member; means in said chuck receptacle for frictionally retaining said chuck member; a cylindrical bore through said scale support communicating with said chuck receptacle; and an elongated slot means in said chuck member disposed transversely of the length of said chuck member and disposed in a position to be placed below said opening when said member is inserted in said receptacle, whereby a chuck wrench having a cylindrical shank and a cylindrical pin eccentrically disposed on the end of said'shank may be placed Within said opening with said pin engaging said slot and `rotated within said opening to apply a force to move said member inwardly and outwardly of said receptacle.

4. In a chuck construction for use with drafting machines employing a scale supporting member, the combination of: a chuck receptacle formed in said scale support having angularly disposed longitudinally extending side surfaces; a chuck member for reception in said chuck receptacle having tapered edge surfaces for engaging said side surfaces of said receptacle to secure said member therein; a cylindrical bore through said scale support communicating with said chuck receptacle; and elongated slot means in said chuck member disposed transversely of the length of said chuck member and in a position to be placed adjacent said lbore when said member is inserted in said receptacle, whereby a wrench having a cylindrical shank and a pin eccentrically disposed on the end of said shank may be inserted within said bore with said p'in engaging said slot and rotated to apply a force to move said member inwardly and outwardly o f said receptacle.

VARD B. WALLACE. 

